The present invention broadly relates to ink jet printers and more specifically, pertains to a new and improved method and apparatus for the ink supply system of an ink jet printer.
Generally speaking, the method and apparatus of the present invention serves for monitoring and regulating the ink droplet velocity in the ink supply system of an ink jet printer having an ink droplet propulsion member, a charging electrode, a charge detector, a deflection electrode and an ink droplet catch gutter. In other words, while the method of the present invention is for monitoring and regulating the velocity of ink droplets in the ink jet of an ink jet printer, the apparatus of the present invention comprises an ink jet regulating system for an ink jet printer and contains an ink jet propulsion device for propelling a rapidly intermittent but continual jet of successive discrete ink droplets in a predetermined forward direction. Regulatable electrostatic charging electrode means serve for imparting an electrostatic charge of predeterminably variable amplitude to the ink droplets. An electrostatic charge detector serves for sensing the electrostatic charge imparted to the ink droplets travelling in the forward direction through the electrostatic charge detector and for generating a feedback control signal proportional to the predeterminably variable amplitude of the electrostatic charge. Deflection electrode means deflect the electrostatically charged ink droplets out of the forward direction in proportion to the amplitude of the electrostatic charge to effect graphic and printing functions of the ink jet printer, and an ink droplet catch gutter serves for catching ink droplets continuing substantially undeflected in the forward direction.
A control arrangement for an ink jet printer is described in German Pat. No. 2,411,822 which comprises a tacho-generator for detecting the printhead velocity and first and second differentiating stages for differentiating corresponding signals. This arrangement is supposed to permit printing operation which is intermittent from character-to-character and has a good print quality.
Other known methods and arrangements for regulating the ink droplet velocity of ink jet printers of the aforementioned type are not suitable for meeting the objects of the present invention which essentially consist in guaranteeing a precise monitoring and regulation of the ink supply system while taking into consideration the rheologic ink properties constantly changing in operation and influencing the operational reliability of the ink jet printer.